This document defines the various terms used in etcd documentation, command line and source code.

Node

Node is an instance of raft state machine.

It has a unique identification, and records other nodes’ progress internally when it is the leader.

Member

Member is an instance of etcd. It hosts a node, and provides service to clients.

Cluster

Cluster consists of several members.

The node in each member follows raft consensus protocol to replicate logs. Cluster receives proposals from members, commits them and apply to local store.

Peer

Peer is another member of the same cluster.

Proposal

A proposal is a request (for example a write request, a configuration change request) that needs to go through raft protocol.

Client

Client is a caller of the cluster’s HTTP API.

Machine (deprecated)

The alternative of Member in etcd before 2.0

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Glossary